The present invention is directed to shift assemblies for motor vehicles, and more particularly to improvements in shift assemblies having an upper lever and a lower lever.
Upper and lower lever type shift assemblies, or xe2x80x9cshiftersxe2x80x9d, are commonly used in motor vehicles to regulate either the transmission or the transfer case of a motor vehicle. In the example of a transfer case shifter, it is common for an upper lever to extend upwardly into a driver""s compartment, and a lower lever operatively connected to the upper lever to extend beneath the floor to the transfer case. Actuation of the upper lever by the operator moves gears of the transfer case to one of several positions. These positions can typically include a 4 wheel drive high speed (4H), suitable for use when added traction is desired, as occurs in adverse weather conditions, a 4 wheel drive low speed (4L,) suitable for use in off-road soft terrain driving where the terrain demands both four-wheel drive and low range power, a 2 wheel drive (2H) suitable for use on normal highways and a neutral (N) position, desirable if the vehicle is to be towed.
Known upper and lower type shift assemblies comprise an upper lever connected to a lower lever by a block mounted inside a housing. The block pivots on a pin mounted on bearings in the housing. Several problems exist with such known designs. The housing typically requires complex machining to prepare an opening for the levers to extend into. Bearings must be inserted with the pin, and welds and/or mounting pins are needed to secure the block with the pin and with the levers. Of course, where mounting pins are used an opening must be provided which typically means additional machining of components. Moreover, when inserting a pin to connect a lever to a pivot block, high stresses may be introduced into the assembled part, reducing overall effectiveness of such assemblies.
There is a need for a shifter with fewer parts, less weight, less tooling and machining requirements and overall reduced cost while at least maintain high quality and reliability in shifting. In view of the foregoing, it is an object of the present invention to provide a shift assembly which is of simple and elegant construction and low cost, and which significantly reduces the overall number of parts and tooling required for assembly. In particular, it is an object of the present invention to eliminate the need for welds and corresponding weld tooling, and to eliminate the need for bearings separate from the housing. It is an additional object of the present invention to provide a shifter that is highly reliable in operation, and which can be manufactured efficiently. Additional objects and optional features of the invention will be apparent form the following disclosure and detailed discussion of preferred embodiments.
In accordance with a first aspect a shift assembly comprises a housing having a top opening and a side opening, an upper lever, a lower lever, a pivot block connecting the upper lever and the lower lever, wherein the pivot block is pivotably mounted in the housing and the upper lever extends through the top opening, and a pivot cover which cooperates with the housing to define a slot. The pivot block extends through the slot, and the pivot cover is connected to the housing by snap fit.
In accordance with another aspect a shift assembly has pivot block, a housing which defines a pocket and a pivot cover which cooperates with the housing to define a generally cylindrical slot, and the slot cooperates with the pocket to define bearing surfaces which receive the pivot block.
In accordance with another aspect, a shift assembly is formed wherein a pivot block and lower lever are formed together as a unitary or one-piece construction.
From the foregoing disclosure and the following more detailed description of various preferred embodiments, it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of shift assemblies.
Particularly significant in this regard is the potential the invention affords for reduced tooling costs and simplified construction of shift assemblies. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.